1. Field of the Invention
This invention relates to a doctor device for a self-washing inking unit of a rotary printing press. The doctor device includes a doctor carrier, on which two doctor blades are attached. The doctor blades are are parallel to each other, and are able to brought into engagement with an inking roller. Together with the inking roller, the doctor carrier, and sealing means provided terminally on the latter, the doctor blades define a closed ink chamber. Ducts for the supply of ink to and removal of ink from the ink chamber are provided, as are loading means for pressing the doctor carrier against the inking roller.
2. Description of the Related Art
An example of a doctor device of this type is described in German patent publication 3,135,711 A, and is schematically illustrated in FIGS. 1 and 2 of the drawings. This doctor device consists of a doctor carrier 1, which, on its side facing the engraved roller 5, has a trough-like recess. The doctor carrier 1 is provided with downwardly sloping, dihedral support surfaces, placed symmetrically relative to its longitudinal median plane II--II. The support surfaces support the doctor blades 7 and 8, which are screwed to the doctor carrier in a known manner using clamping members 30. The ends of the doctor carrier 2 are provided with terminal sheet metal members 3 and 4 in order to produce sealed joints between the doctor carrier and the end faces of the doctor roller 5. Between the terminal sheet metal members 3 and 4 and the end faces of the doctor roller 5, small lateral gaps remain, which make it possible for a reciprocating motion of the doctor device to take place parallel to the longitudinal axis of the doctor roller 5. Besides being sealed off by the two lateral terminal sheet metal members 3 and 4, the ink chamber 2 is sealed off by doctor blades 7 and 8, which are in engagement with the doctor roller 5. It is possible for ink to emerge through the lateral gaps 6. Such ink is then caught by an ink sump 9, provided underneath the doctor roller 5.
The doctor carrier 1 may be pressed against the engraved roller 5 and moved clear of the same by an engaging device which is not illustrated. The ink necessary for printing is pumped through an ink feed hole 10 provided in the doctor carrier 1, and into the ink chamber 2, the excess quantity of ink being returned through the ink return hole 11 into the ink container. This known doctor device operates satisfactorily as such. However, there is a disadvantage, in that it is possible for ink to emerge from the ink chamber through the lateral gaps 6. This ink then has to be caught in an open ink sump 9, and the doctor device will be soiled by the emerging ink. Also, solvent may evaporate from the ink, which then contaminates the atmosphere. Furthermore such evaporation of the solvent means that more solvent is used.